Mining-Chemical Combine Research Articles

Effect of 238Pu Alpha Decay on the Properties of Borosilicate Glass at Experimental and Demonstration Center of Mining Chemical Combine

Effect of 238Pu Alpha Decay on the Properties of Borosilicate Glass at Experimental and Demonstration Center of Mining Chemical Combine

Радиационная обстановка на хвостохранилище Степногорского горно-химического комбината и прилегающих территориях. Сообщение I

Purpose: Assessment of the radiation situation at the tailing dump of the Stepnogorsk Mining-Chemical Combine (SMCC) and the settlements around.
 Material and methods: The tailing dumps of the SMCC and the settlements near located of Aksu, Kvartsytka and Zavodskaya were objects of the radioecological research. Field expedition studies were performed during the summer period and consisted in carrying out a detailed gamma survey of the territory of the investigated objects and settlements, sampling of surface waters, vegetation, surface and layered soil samples. In settlements, along with sampling and studying the gamma background, the equivalent equilibrium volume activity of radon daughters in residential and industrial premises was determined. To determine the concentrations of the studied radionuclides a background was selected, within which the levels of their global deposition were studied. To calculate the individual effective radiation dose of the population the National Radiation Protection Board methodology was used as the basis.
 Results: In the northern part of the tailing dump of the SMCC in the adjoining territory, a radioactive contamination site was found where the specific activity values for 226Ra, 232Th and 210Pb reach values of 1500–2000 Bq/kg. On the territory of the Aksu settlement, 5 local areas with the area from 25 to 1000 m2 were found, with the intensity of ambient dose equivalent of gamma radiation from 0.39 to 0.86 µSv/h. In the Zavodskaya village, two areas with increased levels of gamma radiation intensity were identified. 
 Conclusion: The obtained results of field work and laboratory analytical studies testify to the negative impact of the tailing dump of the SMCC on the environment of adjacent territories, expressed in contamination of soil, water and vegetation with radionuclides. The nature of the abnormal areas on the territory of the settlements of Aksu and Zavodskaya excludes their origin from the tailing dump of the SMCC. The appearance of these areas of contamination may be due to the use of materials of the 3rd class in sanitary and hygienic standards for improvement and road construction. The probable annual effective dose for the population living in the radioactive local areas of the Aksu ~6.5 mSv/year, at the normal rate of 1 mSv/year from man-made radiation sources.

The migration of radionuclide’s for the sanitary protection zone of uranium tailings enterprises (LB488)

Mining companies are potential sources of contamination of the environment by various pollutants, including technogenic radionuclides. Stepnogorsk Mining‐Chemical Combine (SMCC) functions over 50 years and is one of the largest complexes for production of uranium oxide and other rare metals. Radioactive waste of SMCC is accumulated in the tailing dumps with an area of 7.82 km2, located in 4 km to the North from Aksu village and Zavodskoy, where concentrated waste is with a mass of 44.17 million tons, and activity of 146.4 thousand Ku. The aim of this work was to evaluate the radiological situation of territories for sanitary protection zone of the tailings dumps (SZZH), including those in close vicinity to workers of the villages Aksu and Zavodskoy.As a result of the pedestrian gamma survey there were identified local, contaminated sites in the North‐East of SZZH SMCC with a length of 5 km. The most contaminated with radionuclides is the top layer of the soil 0‐5 cm. in the North‐East and South‐East direction from SZZH specific activity is 238U, 226Ra in the soil exceed the reference value in 16 times, 210Pb exceeds up to 7 times. In the samples of plants selected from the vicinity of villages in the South‐East and North‐East directions from SZZH it is noted high concentrations of natural radionuclides. In reservoirs of Sulukamys and Manybay thalwegs, located at a distance of 1.5 to 2 km in the Eastern and North‐Eastern part of the tailings dumps, the specific activity of technogenic radionuclides in the tens times higher than control values.On the territory of the village Aksu there were identified local, contaminated sites with a capacity of an equivalent dose of gamma radiation up to 0.86 mSv / h Possible additional radiation dose from external exposure for separate groups of the population of Aksu is from 0,86 mSv to 1,53 mSv per year.

Cementing technology development for immobilizing pulp from storage containers at the mining-chemical combine

The results of the development work on cementing hydrate-sludge pulp extracted from storage containers at the radiochemical plant of the Mining-Chemical Combine are presented. The work was performed on dummy wastes and real pulp under laboratory conditions as well as on an experimental cementing facility with a pulsation-type mixer developed at the Bochvar All-Russia Research Institute for Inorganic Materials. The properties determining the quality of the cement compound – mechanical strength under compression, water- and frost-resistance, leaching of 137Cs – as well as important technological characteristics, such as cement spreadability and heat release during hydration of the binder were determined for different matrix mixes differing by composition, water/binder ratio, degree of pulp inclusion and form of the binder and sorption additive.

Colloid transport of radionuclides in soils

Radionuclides undergo redistribution and change existence forms (and, therefore, migration dynamics) not only immediately after they enter into the environment, but also during migration. The latter can be associated with changes in the delivery medium (for example, as strongly contaminated wastewaters is diluted by natural), decrease in the concentration of radionuclides (during their sorption and coprecipitation on soil or host rock microparticles), or change in carrier forms (dissolution of fuel matrices). In view of the multifactor nature and complexity of these processes, we set ourselves the task to summarize results obtained at the GEOKHI RAS on the forms of existence and migration dynamics of radionuclides in radioactively contaminated soils. As objects for study we used soils typical of the forest-steppe zone of the Eastern Ural Radioactive Trace (EURT) and taken at a distance of 2 through 8 km from the Trace axis and 2–4 km from the accident place, as well as samples of the high-water bed soils and sediments of the Enisey River, taken 60 km downstream from the Mining Chemical Combine (MCC).

First data on technetium-99 content in the ecosystem of the Yenisei River

The content of a long-lived technogenic radionuclide 99Tc in the Yenisei within the territory of radioactive effluents of the Rosatom mining chemical combine (MCC) has been studied. In 2008–2009 the maximal 99Tc content in water was registered near the dumping site of the MCC and came to 33 mBq/l. According to analysis of filtered water samples, technetium in the Yenisei water is presented as pertechnetate ion (TcO4). When moving away from the MCC downstream, the 99Tc content in water is decreased, which is caused both by dilution of waste water and by 99Tc accumulation by aquatic plants. The 99Tc content in the biomass of the aquatic plant Potamogeton lucens came to 8215 Bq/kg, and the concentration factor (CF) to 8200, which is three times more than the maximal values of the CF of 99Tc by the plants in laboratory conditions (2700).

Investigations of the Microwave Electromagnetic Properties of Pulp with Fluxing Additives

Vitrification of pulp-like radioactive materials with production of borophosphate and borosilicate glasses, using microwave energy at 2375 MHz and output generator power 5 kW, have been studied at the Mining-Chemical Combine since 1999. The conditions for heating the material being processed depends strongly on the electromagnetic characteristics of this material, specifically, the permittivity and the tangent of the dielectric loss angle. Investigation of the electromagnetic characteristics of the processed material and their analysis will make it possible to generate recommendations for effective execution of the process of vitrification of radioactive pulps using microwave energy. As a result of the investigations, the permittivity and tangent of the dielectric loss angle of a pulp simulator, evaporated conglomerate (calcinate), and samples of glasses obtained from this pulp were measured, the materials increasing the dielectric losses of the calcinate at microwave frequencies were determined, and the dynamics of the variation of the electromagnetic properties of the pulp as a function of the content of the additives which increase the tangent of the dielectric loss angle was determined.

Investigation of the Tritium Transport by Water Flows from the Territory of the Mining-Chemical Combine in Krasnoyarsk

Investigation of the Tritium Transport by Water Flows from the Territory of the Mining-Chemical Combine in Krasnoyarsk

Investigations of the Nizhnekanskiy Granitoid Massif (Middle Siberia, Russia) as a Promising Territory for Deep Geological Disposal of HLW: Results of Pre-Exploration Stages of the Work

AbstractTo decide the final fate of high-level radioactive wastes that are in Krasnoyarsk Land, Russia, and, most importantly the wastes from a weapons complex at the Mining-Chemical Combine (MCC, Krasnoyarsk-26), suitable sites for geological disposal of the wastes are being sought in Middle Siberia. The ultimate goal is to select one site for development of a repository for these wastes. As a result of complex geological-geophysical work completed to date, the two most promising sites are in the northern part of the Nizhnekanskiy granitoid massif (the Yenisei Ridge). These sites are approximately 25 km from the MCC. Based on geotectonic analysis and electrical surveying data, these sites are composed of low-permeability biotite granite that extends to relatively great depth. At present, both sites are undergoing more detailed studies to define the most suitable one for detailed geological exploration. Radiogeochemical studies showed that granitoid rock samples from the massif exhibited high retention for major long-lived radionuclides in the wastes. The general results of the investigations are presented.

Hydraulic-fill construction and operation of a tailings pond

1. As shown by the experience with operation of tailings ponds [5, 6] formed by the hydraulic-fill method with dispersed sludge discharge, the construction of stable toes in the tailings pond is ensured. 2. Underwater hydraulic-fill placement of tailings having more than 70% of particles smaller than 0.074 mm is not recommended. In exceptional cases, underwater hydraulic-fill placement of such tailings may be carried out only after smoothing the irregularities, pits, trenches, and ditches, and only when further grading of the zone is performed whether with subsequent above-water hydraulic filling or by other (dry) methods applied with mining engineering reworking, as well as when there are no structures and no new projects are to be constructed in the zone. 3. Use of the relations described above makes it possible to determine the distribution of the particles and the regimens of hydraulic-fill placement of fine tailings in a tailings pond for dispersed sludge discharge, and is effectively confirmed in industrial practice. For example, for the tailings obtained from the processing of sulfur ores at the Rozdol'sk Mining-Chemical Combine [7], which contain particles smaller than 0.074 mm in amounts of 75–85%, the rate of hydraulic-fill placement of stable toes is 2.5–3.5 m/yr, whereas in the case of hydraulic filling of patterns for stockpiling of limestones fertilizers under a forced regimen the rate is 6–7 m/yr, which indicates the potentialities of the hydraulic-fill techniques. This will make it possible to increase the volume of stockpiling and shipping of mineral fertilizers of the combine to 3 million tons per year, that is, to increase the production of these limestones by a factor of almost two and to obtain a significant economic effect on account of a reduction in the contingent-fixed costs and other expenditures.